The synthesis and coordination properties of heterocyclic receptors and sensors for anions
The synthesis and coordination properties of heterocyclic receptors and sensors for anions
Two calix[4]pyrrole macrocycles have been synthesised containing a ferrocene redox active group in one of the meso-positions. These receptors co-ordinate a variety of anions in solution. 1H NMR analysis of the receptors in the presence of anions revealed a downfield shift of one ferrocene proton, this provided evidence for a direct co-ordination mechanism between the anion binding site and the redox reporter group. Electrochemical studies revealed cathodic shifts with all anions, up to 100 mV with dihydrogen phosphate. A pentapyrrolic calix[4]pyrrole was synthesised bearing a single pyrrole pendant arm in the meso-position. This receptor displayed an enhanced affinity for all anions when compared to meso-octamethylcalix[4]pyrrole. The selectivity displayed by this receptor for carboxylates was investigated using molecular modelling that suggested both of the carboxylate oxygens were simultaneously co-ordinated.
A variety of furan and thiophene based amide and thioamide clefts have been synthesised. Introduction of the thioamide functional group displayed a moderate increase in anion binding affinity when compared to the corresponding amide derivatives, whereas the heteroatom was seen to alter the receptor selectivity. The furan based receptors revealed up to a 40-fold selectivity for fluoride over other anionic guests, while the thiophene receptors selectively bound dihydrogen phosphate. The phenylamide thiophene receptors gave strange titration profiles with fluoride, believed to be caused by multiple equilibria processes occurring in solution. However, addition of fluoride and other basic anions to these receptors produced a colourless to yellow colour change, possibly allowing colourmetric sensing of basic anions by these receptors. A crystal structure revealed the formation of thiophene CH...anion hydrogen bonds in the solid state, while a mono-amide substituted thiophene receptor provides further evidence for this interaction in solution.
University of Southampton
Warriner, Colin Neil
097b84b9-fb34-4ee6-98f8-883767598f7c
2004
Warriner, Colin Neil
097b84b9-fb34-4ee6-98f8-883767598f7c
Warriner, Colin Neil
(2004)
The synthesis and coordination properties of heterocyclic receptors and sensors for anions.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Two calix[4]pyrrole macrocycles have been synthesised containing a ferrocene redox active group in one of the meso-positions. These receptors co-ordinate a variety of anions in solution. 1H NMR analysis of the receptors in the presence of anions revealed a downfield shift of one ferrocene proton, this provided evidence for a direct co-ordination mechanism between the anion binding site and the redox reporter group. Electrochemical studies revealed cathodic shifts with all anions, up to 100 mV with dihydrogen phosphate. A pentapyrrolic calix[4]pyrrole was synthesised bearing a single pyrrole pendant arm in the meso-position. This receptor displayed an enhanced affinity for all anions when compared to meso-octamethylcalix[4]pyrrole. The selectivity displayed by this receptor for carboxylates was investigated using molecular modelling that suggested both of the carboxylate oxygens were simultaneously co-ordinated.
A variety of furan and thiophene based amide and thioamide clefts have been synthesised. Introduction of the thioamide functional group displayed a moderate increase in anion binding affinity when compared to the corresponding amide derivatives, whereas the heteroatom was seen to alter the receptor selectivity. The furan based receptors revealed up to a 40-fold selectivity for fluoride over other anionic guests, while the thiophene receptors selectively bound dihydrogen phosphate. The phenylamide thiophene receptors gave strange titration profiles with fluoride, believed to be caused by multiple equilibria processes occurring in solution. However, addition of fluoride and other basic anions to these receptors produced a colourless to yellow colour change, possibly allowing colourmetric sensing of basic anions by these receptors. A crystal structure revealed the formation of thiophene CH...anion hydrogen bonds in the solid state, while a mono-amide substituted thiophene receptor provides further evidence for this interaction in solution.
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Published date: 2004
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Local EPrints ID: 465289
URI: http://eprints.soton.ac.uk/id/eprint/465289
PURE UUID: 67593a29-1486-4f49-866c-19e22e2db926
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Date deposited: 05 Jul 2022 00:35
Last modified: 16 Mar 2024 20:05
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Author:
Colin Neil Warriner
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